Automatic feed for cable-tool drill



Aug. 9, 1955 w THQRNBURG 2,715,015

AUTOMATIC FEED FOR CABLE-TOOL DRILL Filed Sept. 25, 1955 s Sheets-Sheet 1 HERBERT N -THOENBUR E;,

JNVENTOR,

AIT RN E X g- 9, 1955 H. w. THORNBURG AUTOMATIC FEED F OR CABLE-TOOL DRILL I5 Sheets-Sheet 2 Filed Sept. 25, 1953 HERBERT W.THORNI5UR I,

IN V EN 'I'OR,

ATTORNEY.

Aug. 9, 1955 w. THORNBURG AUTOMATIC FEED FOR CABLE-TOOL DRILL 3 Sheets-Sheet 3 Filed Sept. 25, 1953 1 M H UR Bm R WN M 0 E r OV HN T. A w W l R m M R W E H Y B a no 1 United States Patent 0 AUTOMATIC FEED FOR CABLE-TOOL DRILL Herbert W. Thomburg, South Milwaukee, Wis., assignor to Bucyrus-Erie Company, South Milwaukee, Wis., a corporation of Delaware Application September 25, 1953, Serial No. 382,317

8 Claims. (Cl. 255-15) This invention relates to new and useful automatic feeds for cable-tool drills, more particularly for such drills actuated hydraulically.

Such drills, per se, are well known.

In such drills, a rope passes, from a winch-drum on the main frame, thence over or under one or more sheaves, one of which is usually at the upper end of a mast, and from this latter sheave vertically downward into the hole which is being drilled in the ground. At the lower end of this rope is a string of drilling-tools, terminating in a percussion bit. One of the sheaves, over or under which the rope passes, is reciprocable by appropriate associated means (for example, an hydraulic cylinder-piston assembly) whereby the bit is rapidly alternately raised and then dropped, to drill the hole.

As the hole grows deeper, it is necessary that the winch drum shall unwind to pay out more rope. In the past, this paying-out has been effected in one of the following three ways: (1) Time control, in which the winch steadily or intermittently unwinds with the mere elapse of time. (2) Non-automatic, the operator voluntarily running the winch whenever more rope was needed. (3) Shock control, a brake being set on the winch to yield at a certain predetermined torque, so that the shock of the tools falling and not striking bottom would jerk out a trifle more of rope. (4) Automatic positive, in which, in response to increased tension in the rope whenever the tools fall and fail to strike bottom, the winch is positively unwound a predetermined amount.

Method 1 was wholly unsatisfactory, except in very uniform steady drilling. Method 2 required too much careful attention by the operator. Method 3 required too precise an adjustment of the brake, the proper adjustment depending too much on various variable conditions, such as atmosphere, lubrication, etc., and furthermore required that that precise adjustment be exactly maintained. Method 4, although quite satisfactory, was sufficiently complicated and expensive to lead to the need of a less complicated and expensive alternative mechanism.

Accordingly it is the principal object of the present invention to devise a feed which shall pay out additional rope, when and as needed, without being open to any of the above objections.

The present invention employs none of these alternatives. Instead it takes advantage of certain inherent characteristics of the particular type of hydraulic spudding employed by the drill for use with which my feeding device was designed. In such a drill, the hydraulicallyactuated spudding mechanism, during each lowering of the bit, is automatically reversed (to raise the bit) just before the bit reaches its lowest point of fall. This sets up back-pressure in the hydraulic circuit which leads to the spudding-motor. As the hole grows deeper, and consequently the bit fails to bottom, this back-pressure increases. There is employed a hand-set brake to prevent unspooling of the winch; but instead of setting this brake loosely and then depending on a yank on the cable to feed the cable, there is employed the increased back 2,715,015 Patented Aug. 9, 1955 pressure to hydraulically release the brake momentarily, thus feeding out cable in proportion to the excess of back-pressure, which in turn is proportional to the degree of failure to bottom.

Thus in the present invention the Winch is softly and smoothly unwound, a very small distance, as needed, to maintain substantially uniform percussion at the bottom of the hole.

The present invention consists in the novel parts and in the combination and arrangement thereof, which are defined in the appended claims, and of which one embodiment is exemplified in the accompanying drawings, which are hereinafter particularly described and explained.

Throughout the description, the same reference number is applied to the same member or to similar members.

Figure l is a side elevation of a drill embodying my invention.

Figure 2 is an enlarged plan view, partly in section, of the main machinery of my drill.

Figure 3 is an enlarged side elevation of said machinery.

Figure 4 is a largely diagrammatic representation of the essential elements of my invention, and the essential cooperating elements of the spudding mechanism.

Turning now to Figure l, 11 is seen to be the main frame of the drill, supported by creeping traction 12.

13 are jacks, to level a frame 11, and to steady it during digging.

The frame 11 supports a mast 14 (called derrick in the art). Also a motor 15, which serves to propel the creeping traction 12, to spool the winch-drum 16, and to drive the fluid-pump 33 (not shown in this figure).

From the winch-drum 16, a cable 17 extends upwardly and over a spudding-sheave 118, journaled in a sheave block 19, which is slidably mounted at the top of the derrick 14, in any convenient manner for limited sliding up and down. Thence the cable extends downwardly to support and reciprocate a string of drillingtools 20, ending in a drill-bit 21, shown in the well-hole 22, which it has just started to dig.

23 is a tool-guide, supported by the derrick 14.

At the foot of derrick 14, there is to be seen an hydraulic cylinder-piston assembly 24, the piston-rod 25 of which extends up the derrick to support and reciprocate sheave-block 19, thus constituting one form of reversible fluid motor means. When in the claims there is reference to a reversible fluid motor means, this is not intended to be limited to means in which the direction of rotation or reciprocation of the motor proper is reversed, but rather to include as well means in which the reversing of the effect of the motor is accomplished by reversing some driven means associated with the motor proper.

There is also shown, in Figure 1, the brake-band 26 for brake-drum 27, which is associated with winch-drum 16 to I keep it from unspooling, and hand-lever 28 for setting the brake at will.

Many other conventional elements of the drill have been omitted from this showing, inasmuch as they have no particular bearing on the invention, the object of Figure 1 being merely to give an overall picture of the drill.

Turn now to Figures 2 and 3 for a more detailed show ing of so much of the machinery as directly concerns the invention.

Motor 15, through drive-pulley 29, band 30, and drivenpulley 31, drives shaft 32, which in turn drives hydraulicpump 33. This pump is supported on a sideward extension (not shown) from main frame 11.

Through clutch mechanism 34, shaft 32 can drive sleeve 35, thence pinion 36, thence gear 37, thence shaft 38, thence pinion 39, and thence gear 40, which is integral with Winch-drum 16.

Also integral with winch-drum 16 is brake-drum 27.

3 Brake-band 26, associated therewith, can be set by appropriate linkage 41, by counterclockwise rotation of the far end of shaft 42, the nigh end of which is rotatable by hand-lever 28, which can be caught in various degrees of brake-setting by serrated catch 43.

The brake-unsetting mechanism (shown at the far end of shaft 42 in Figure 2, and between hand-lever 28 and winch-drum 16 in Figure 3) will be more particularly described hereinafter.

Turn now to Figure 4, in which the wide pipes represent the principal hydraulic circuits, and the narrow pipes represent the auxiliary circuits of the servo mechanism.

50 is a tank for hydraulic fluid. Pump P draws hydraulic fluid through pipe 51 and impels it through control valve V into pipe 52, thus serving as a source of hydraulic fluid under pressure. Pipe 52 carries this fluid to reversing valve 53.

Pipe 54 carries fluid under pressure from pipe 52 to rotary pilot-valve 55, the rotary member 56 of which swings back and forth through 45 degrees, under the influence of trip-dog 57. The two extreme positions of rotary member 56 and of trip-dog 57 are shown: one position full, the other position dotted. The fact that tripdog 57 controls rotary member 56 is indicated by the dotdash line connecting their respective centers.

Drain-pipe 53 extends from reversing-valve 53 to tank 50. Drain-pipe 59 extends from rotary pilot-valve to drain-pipe 58.

In each of drain-pipes 58 and 59 there is an adjustable restriction, 60 and 61 respectively. The object of restriction 60 is to prevent spudding-sheave 18 from overrunning rope 17, when reversing-valve 53 is set to lower the bit. The object of restriction 61 is to control the speed with which reversing-valve 53 shifts.

Pipes 62 and 63 extend from rotary pilot-valve 55 to opposite ends of reversing-valve 53, to operate the latter.

Pipe 64 extends between reversing-valve 53 and cylinder-piston assembly 24, and serves alternately as a pressure pipe and as a drain-pipe, depending on the setting of the valve.

Pipe 65 extends from cylinder-piston assembly 24 to tank 65, and serves as an air-vent for the upper end of the cylinder.

Trip-fingers 66 and 67 are adjustably secured to rod 68, which reciprocates with piston-rod 25. Black trip-finger 66 is in the same plane as the black prong of trip-dog 57, and white trip-finger 67 is in the same plane as the white prong of the trip-dog; but these two planes are different. As shown in Figure 4, piston-rod 25 is completing its descent, and trip-finger 66 has just tripped trip-dog 57 into r its shown position, thus shifting rotary member 56 of pilot-valve 55 into its shown position. Pressure-fluid from pipe 54 has thus been admitted, via pipe 65, to the righthand end of the reversing-valve 53, thus shifting plunger 69 thereof to the left, and forcing the trapped fluid in the left-hand end of the reversing-valve through pipe 63, valve 55, pipe 59, and pipe 58, into tank 50. The left-hand position of plunger 69 is admitting pressure-fluid from pipe 52, via pipe 64, into the bottom of cylinder 24, to raise the piston and piston-rod 25.

When trip-finger 67 engages the white prong of trip-dog 57, near the top of the stroke, this will rotate the trip-dog and rotatable member 56 of pilot-valve 55 clockwise 45 degrees, into the dotted-line position, with the result that pressure-fluid from pipe 54 will now go, through pipe 63, to force plunger 69 to the right, thus forcing the trapped fluid in the right-hand end of reversing-valve 53 out through pipe 62, pilot-valve 55, pipe 59, and pipe 58, into tank 50. The right-hand position of plunger 69 will cause the pressure-fluid from pipe 52 to by-pass, through pipe 58, to tank 50. Under the weight of the tools on cable 17, piston rod 25 will descend, forcing fluid out of the lower end of cylinder 24, through pipe 64, reversing-valve 53, and pipe 58 to tank 50.

All the foregoing, except the description of the winchbrake mechanism, is mere setting for the present invention.

70 is a side-conduit off of pressure-pipe 52. This sideconduit leads to a small cylinder-piston assembly 71, the piston-rod 72 of which is operatively attached to shaft 42 of the winch-brake mechanism, through link 73.

En route, side-conduit '70 is divided into two branches. The upper branch 74 is for the purpose of conveying liquid to the right; the lower branch 75 is for the purpose of conveying liquid to the left. In the upper branch 74, an adjustable relief-valve 76 prevents the advent of pressurefluid from pipe 52 to cylinder-piston assembly 71 at ordinary spudding pressures. In the lower branch 75, there is a simple check-valve 77, which serves to prevent fluid, en route from pipe 52 to cylinder-piston 71, from by-passing relief-valve 76 at pressures less than the relief-valve is set for.

It is necessary that the return circuit from cylinderpiston assembly 71 lead to pipe 52, rather than to tank 50; for if it led to tank 50, then when liquid, under excess back pressure in pipe 52, is passing through relief-valve 76 to actuate cylinder-piston assembly 71 to unset the brake, this liquid would by-pass to the tank, instead of performing its function.

In the present exemplification of my invention, branches 74 and 75 of side-conduit 7 0, and valves 76 and 77, therein, are all built in one unit, indicated as 78 in Figures 2 and 3.

Vent-pipe 79 extends from cylinder-piston assembly 71 to tank 50.

It is necessary that there be resiliently yieldable means, so positioned as to maintain the brake set, whenever brake-lever 28 is set, except whenever the brake is being unset by the excess back-pressure in pipe 52.

This yieldable means should be sufliciently resilient to set up in cylinder-piston assembly 71 a back-pressure intermediate between the normal spudding-pressure in pipe 52, and the excess pressure at which relief-valve 76 is adjusted to open.

Branches 74 and 75 of side-conduit 70, and valves 76 and 77 therein, could be omitted, in which event the resiliently yieldable means (preferably adjustable, as for example by a fine degree of setting of control-lever 28) could be employed to predetermine the amount of hydraulic back-pressure necessary to release the brake. But preferably elements 74 to 77 should be retained, for without relief-valve 76 the brake would ease on and off, instead of snapping on and off, and hence fine control of feeding would not be possible.

In the present exemplification shaft 42 (because of the long distance between the control-lever 28 at one end, and the brake-band-setting linkage 41 and the brakeband-unsetting link 73 at the other end) constitutes a torque-rod, and hence serves as my resiliently yieldable means. The hand-lever 28 itself may also or alone serve as the resiliently yieldable means.

The operation of my invention may be summarized as follows.

The winch-drum brake is set by hand-lever 28, pump P is running, valve V is open and cylinder-piston assembly 24 is reciprocating.

When pilot-valve 55 is in its dotted-line position as shown in Figure 4, piston-rod 25 drops (under the infiuence of the weight of the tools pulling on rope 17), and trip-finger 66 hits the black prong of trip-dog 57, thus rotating the trip-dog and rotary member 56 of pilot-valve 55 counterclockwise 45 degrees, to the full-line position shown. This position causes plunger 69 of reversingvalve 53 to shift to the left to the position shown.

Piston-rod 25 continues momentarily to descend, although the reversing-valve is now set to raise the piston.

Normally bit 21 will new hit the bottom of the wellhole, and will bounce, and thus the weight of the string of tools will not oppose the reversal of the piston.

But if the hole has been dug away from the bit, the bit will fail to bottom and to bounce, and will still be falling when pressure-fluid enters the bottom of cylinder 24 through pipe 64. The downward pressure of the piston, clue to the still falling of the tools, will set up a backpressure in pipe 52 to oppose the pump-pressure, thus squeezing out a shot of hydraulic fluid, through reliefvalve 76, into cylinder-piston assembly 71, to release the brake momentarily and thus pay out about an eighth of an inch or so of cable.

The excessive back-pressure lasts for only an instant. As soon as it is relieved, the resilience of torque-rod 42 resets the brake and forces the piston of 71 back up again, thus discharging the spent liquid from cylinder 71, through check-valve 77, back into pipe 52, where the pressure by now is not sufficient to oppose this.

The amount of cable thus paid out by each occurrence of excessive back pressure due to non-bottoming, is so slight that practically uniform percussion, stroke after stroke is obtained.

In drills of the prior art, at the beginning of each run, the bit is customarily lowered until slack in the cable indicates that the bit has fully reached the bottom of the hole. The operator thereupon winds-up the winch, to raise the bit about three or four inches. Spudding is then started, and the proper length of cable is gradually adjusted by whatever feed-mechanism is employed.

But in the type of drill for which the present invention is designed, when the machine is at rest the piston of cylinder-piston assembly 24 rests at the bottom of the cylinder, a position considerably below the lowest ever attained by it during the spudding cycle. Accordingly with the present invention, the operator does not have to juggle the bit after lowering, but can leave it at the bottom of the hole, and start spudding. The commence ment of the spudding operation will pick up the bit sufliciently, and the complete non-bottoming will thereupon cause the feed-mechanism to adjust the proper cable-length during the first three or four spudding strokes.

One form of the invention having now been described and illustrated, it should be understood that the invention is not to be limited to the specific form or arrangement of parts herein described and shown.

I claim:

1. In an automatic hydraulic feed for an hydraulic cable-tool drill, such drill comprising: a reversible winchdrum; means for driving said drum at will; a percussion drill-bit; a cable wound upon said drum and extending to support said bit; a spudding-sheave, supporting said cable at a point intermediate said drum and said bit; and hydraulic means for reciprocating said sheave to raise and lower said bit; said reciprocating means including a source of hydraulic-fluid pressure, reversible fluid motor means, means operatively connecting said motor means to said sheave to reciprocate said sheave, an hydraulic circuit extending from the source to the motor means, said motor means and said circuit being such that resistance to said motor means when set for bit-raising will create back-pressure in said circuit, and means automatically responsive to the position of the sheave to reverse the motor means from bit-lowering to bit-raising shortly before each time the sheave reaches its extreme bit-lowering position at the bottom of the drilling stroke; all the foregoing constituting merely the setting for the automatic feed; the combination of: a brake for the drum; means for setting the brake at will; hydraulic means for momentarily releasing the brake in response to hydraulic pressure beyond a predetermined amount;

and an hydraulic side-conduit extending from the hydraulic circuit to said brake-releasing means; whereby excessive back-pressure in the circuit at the bottom of the drilling stroke, due to the bit not bottoming, will send a shot of liquid through the side-conduit to momentarily release the brake, thus paying out a small amount of cable.

2. An automatic feed according to claim 1, characterized by the fact that the brake-setting means comprises: a control-lever; holding means for the lever; and resiliently yieldable means operatively connecting the controllever to the brake, to force the brake into set condition when the control-lever is held by the holding means; whereby the resilience of the resiliently yieldable means is what predetermines the amount of hydraulic pressure necessary to release the brake.

3. An automatic feed according to claim 2, further characterized by the fact that the resiliently yieldable means is a long shaft which serves as a torque-rod; that the control-lever is operatively connected to the shaft to rotate the shaft; that there is a brake-setting lever operaively connected to the shaft at a point remote from the control lever, to be swung through an are by the shaft; and that the hydraulic brake-release means is operatively connected to the shaft at a point remote from the control-lever.

4. An automatic feed according to claim 1, characterized by the fact that the brake-setting means comprises: a control-lever; holding means for the lever; and resiliently yieldable means operatively connecting the controllever to the brake, to force the brake into set condition when the control-lever is held by the holding means; and by the fact that the hydraulic release means comprises a cylinder-piston assembly, which when actuated by the shot of liquid, opposes the resilience of the resiliently yieldable means, and thereby releases the brake.

5. An automatic feed according to claim 1, characterized by the fact that there is interposed, in the sideconduit, valve-means which includes pressure-responsive means which predetermines the amount of pressure necessary for liquid to reach the brake-release means to actuate the brake-release means.

6. An automatic feed according to claim 5, further characterized by the fact that the valve-means also includes a by-pass around the pressure-responsive means, and that there is in this by-pass a check-valve to prevent the flow of liquid toward the brake-release means, but permitting return flow.

7. An automatic feed according to claim 1, characterized by the fact that there is interposed, in the sideconduit, valve-means which includes adjustable pressureresponsive means which predetermines the amount of pressure necessary for liquid to reach the brake-release means to actuate the brake-release means.

8. An automatic feed according to claim 7, further characterized by the fact that the valve-means also includes a by-pass around the pressure-responsive means, and that there is in this by-pass a check-valve to prevent the flow of liquid toward the brake-release means, but permitting return flow.

References Cited in the file of this patent UNITED STATES PATENTS 

